Cooling combustion turbines



Aug. l1, 1953 s. cAMPlNl '2,648,519

COOLING coMBUsTIoNf TURBINE Filed April 22, 1948Y SECONDOCAMPINI.

un-4, L5M# 55 ATTORNEYS.

Patented Aug. 11, 1953 UNITED STATES FATENT OFFICE COOLING COMBUSTION TURBINES Secondo Campini, Milan, Italy Application April 22, 1948, Serial No. 22,535

a claims. (o1. 253439.15)

This invention relates to improvements in cooling means for gas or internal combustion turbines, particularly of the type employed for jet propulsion of planes and the like, and comprising an air compressor, fuel burning means in the compressor output for providing a jet propulsion reaction, and a gas turbine driven by the combustion products for driving the compressor.

Objects of the invention are to provide highly eicient and effective means for cooling the iixed and rotating parts of gas turbines which are exposed to the heated gases, such as the rotor and stator elements, as well as to provide means for cooling the turbine housing or casing.

Arrangements have heretofore been proposed for cooling the rotor and contiguous stator components, in gas turbines of the character aforesaid, but such prior proposals entail certain limitations upon the metals employed in the turbine construction, in order that the desired temperatures can be achieved, in consequence of which they do not permit the construction of gas turbines of high thermal eciency. Thus, a serious limitation has been placed upon the power of prior gas turbines per pound oi compressed air. The present invention permits the construction of a gas turbine of the type aforesaid, having a thermal efficiency which is equal to or greater than that of the conventional internal combustion engine of the reciprocating piston type. Moreover, the present invention permits the attainment of a power output which is more than double the power output of comparable gas turbines proposed in the past.

In accordance with one modication of the invention, the gas turbine may take the form of a disc-like rotor provided with peripherally disposed Vanes or buckets for driving the saine, the rotor being rotatably mounted within a turbine housing or jacket, which mounts and supports a stator ring provided with guide vanes or nozzles for directing the hot gaseous combustion products against the rotor vanes or buckets for driving the same. The stator ring is thus mounted in both radially and axially spaced relation to the rotor, in conjunction with which the basal portions of the rotor and stator elements are so concavely shapedy viewed in axial section, as to provide a passage for the injection and now of cooling air therebetween, this cooling air being supplied from the compressor, and being injected therefrom axially between the stator ring and rotor shaft in the annular passageway provided between them, as above explained, and ilowing thence radially outward between thev opposed,

spaced rotor and stator elements against the rotor and stator vanes, at which point it meets the hot gases from the combustion chamber, from whence the combined combustion gases and cooling air are swept past the rotor vanes and discharged through the discharge or jet nozzle of the turbine. In order to prevent the hot combustion gases derived from the combustion chamber of the turbine, from flowing into the cooling air passageway between the rotor and stator elements, the pressure of the cooling air supplied to this passageway from the compressor must exceed the pressure of the hot combustion gases against the turbine blades.

For enchancing the cooling action of the rotor and stator elements due to the ow of cooling air therebetween, as above described, the opposed surface portions of the rotor disc and stator ring,v

which are situated just below the vanes, are provided with a series of heat-dissipating ribs or ns. These iins may be angularly spaced and extend radially outward in rectilinear or suitably curved manner for centrifugally throwing the cooling air against the rotor vanes, but, in accordance with animportant feature of the invention, preferably take the form of a series of radially spaced rings, concentric with the axis of the rotor element. It is found that this latter arrangement greatly increases the cooling action of the rotor and stator elements as compared to the radially extending fin arrangement. It will be understood, of Course, that it is within the contemplation of the present invention to provide these cooling ns on either the rotor element alone. or on the stator element alone, but preferably they are provided on both of these elements in the ways above described, since this imparts the greatest cooling action to both the rotor and stator elements.

In accordance with a further modidcation of the invention, stator rings, constructed as aforesaid, are mounted on opposite sides of the stator disc, in axially spaced relation thereto, to provide radially extending cooling air passageways aforesaid, and at least one of these stator rings is also radially spaced from the rotor shaft to provide therebetween, an annular passageway for the injection of cooling air from the compressor, in addition to which the rotor disc is transversely perforated or slotted at angularly spaced intervals to interconnect the radially extending cooling air passageways aforesaid on the opposite sides thereof. lThus, the cooling air introduced from the compressor will flow in part radially outward in the cooling air passageway on one side of the rotor disc, and will flow in part through the 'oerforations or slots therein into the cooling air passageway on the opposite side thereof and ther ce radially outward between the opposed roto." and stator ring surfaces.

In accordance with still another modification of the invention, which is applicable to any of the constructions above described, the turbine housing or casing takes the form of an inner jacket and an outer jacket which are so mounted as to provide an air space therebetween, into whichv cooling air may be injected fromthecompressori for cooling the turbine casing, the inner casing being suitably perforated or slotted adjacentthe rotor vanes or buckets to provide exits, through which the cooling air flowing between these turbine jackets is expelled against the vanes or buckets of the rotor element.

The slotted rotor construction above described is.A applicable to singlefstageaswell as to multifstage turbines.

As a further refinement of the invention, additionalV heat-dissipating. fins may be provided on the outer peripheries of thev vanesor buckets of the rotor elements, thesel fins preferably being axially spaced along these. vanes and extending peripherally thereabout, in the form of a peripherally grooved outer ring. In conjunction with this construction, the exit slots provided in the inner turbine j acket` areso formed andpositioned as to direct. the cooling air expelled. therefrom, against the heat-dissipating fins thus provided at the outer peripheries` of the: rotor vanes.

With referenceto theturbine casing construction aforesaid, comprising inner and outer, spaced jackets, there are provided, in accordance with a further feature of the invention, on a surface or surfaces-of either or both of these jackets, a series` of heat-dissipating, ns, which preferably take the form of axially spaced ribs extending peripherally aboutthe jacket or-jackets, the preferredarrangementbeing that wherein such fins are providedV on the innerl surface or surfaces of the jackets, andsuch thaty the cooling air from the compressoris caused to, ow along these beforesaid ns.

In order to prevent overheating of the cornbustion chambers aforesaid, I provide, in accordance with still another feature of theinvention, a series of heat-.dissipating ilnson the outer surfaces of such chambers, these hns being pref.- erably angularly spaced and. extending axially along the outerV surfaces thereof.

In accordance with still` another feature4 of the invention, the. coolingk air fromthe compressor is circulated througha water-cooled, or other liquid-cooled, cooling means prior to entering the cooling passages of the turbine above described.

Having thus generally described my invention, reference will now be had, for a more detailed description thereof, to the accompanying drawings, wherein:

Fig. l is a view in axial, sectional elevation of a portion of a gas turbine embodying coolingl means in accordance with one modification of the invention, this view showing a rotor wheel and contiguous stator rings, together with the associated portion of the turbine housing. Fig. 2 is a view in front elevation of a portion of the turbine Wheel of Fig. 1, as taken as 2-2 of Fig. 1.

Fig. 3 is a view in axial, sectional elevation of a fragmentary portion of a turbine wheel and contiguous stator and turbine housing components, illustrating another modification of the invention.

Fig. 4 is a view in axial, sectional elevation of a fragmentary portion of a turbine rotor wheel, illustrating a further modification of the invention.

Fig. 5 is a view in axial, sectional elevation of a portion of a multi-stage turbine embodying cooling means in accordance with a further modification of theY invention, this view showing a rotor and contiguous stator elements, and also a portion of the turbine housing.

Fig. 6 is a view in axial, sectional elevation through a multifstage gas turbine and associated t combustion chamber and air compressor units,

illustrative. of still a further modification of the invention.

Referring to Figs. 1 and 2, there is shown generally at I0, a portion of a gas turbine in accordance with one modification of the invention, asabove described, and comprising a. rotor disc II, rotatably mounted, on a shaft I2, the outer periphery of the rotor disc having keyed thereto, in the manner illustrated at I3, a series of angularly spaced airfoil vanes or buckets I4 for impelling the same. The rotor is enclosed within a turbine housing shown generally at I5,4 and comprising an inner jacket I6 and an outer jacket Il, mounted in spaced-apart relation, as shown, and for purposes above described and as. explained more in detail hereinafter. Secured to and. carried by the inner jacket I5, are a pair of stator rings I8 and I9, which are mounted respectively on opposite sides of the rotor disc II, as shown, these stator rings. being provided with guide vanes, as at 20 and 2I, for

directing hot combustion gases from the com-l bustion chamber, against and respectively away from the rotor varies I4. The basal portions of the stator rings I8, I9v are of solid construction, as shown at 22, 23. Also, the stator rings are mounted in axially spaced relation to the rotor, as shown at 24, 25. In addition, the basal portions of the stator rings and the rotor disc are concavely shaped, viewed in axial section, as illustrated in Fig. l, whereby the spacings 24 and 25 provide radially extending air passages on both sides of the rotor, for the flow of cooling air therethrough as above explained. The stator ring 22 on the inlet side is radially spaced from the rotor shaft, as shown at 2 5, to provide an annular passageway, as shown, between thebase of the stator ring 22 and the rotor shaft, for injection of cooling air from the compressor into the radially extending cooling passageway 24. Moreover, the rotor disc II is transversely slotted or apertured, at angularly spaced intervals, in the manner shown at 2l, for interconnecting the radially extending passageways 24 and 25, on the opposite sides of the rotor disc respectively. In this way, cooling air injected from the compressor into the annular passageway 26, will flow, in part, radially outward through passageway 24 on one side of the rotor against the vanes 2D, I4; and will also ilow, in part, through the rotor disc slots 2l into the passageway 25 on the opposite side of the rotor disc, and thence radially outward against the vanes I4, 2| thereby cooling both surfaces of the rotor disc, and also the theretoopposed surfaces of the stator rings. In turbines of the multi-stage type, the base of the stator ring 23 will likewise be radially spaced from the rotor shaft I2 to provide an annular passageway therebetween, as. at. 28, connecting the radial air cooling passageway with passageways corresponding to 24, 21 and 25 of the next succeeding stage, as explained more in detail below. On the other hand, and in turbines of the single-stage type, the annular passage 28 is preferably closed or blocked off, by means of a closure member, as indicated, for example, by the closure plate 28a, thereby to prevent the escape of the cooling air through the passageway 23.

For enhancing the cooling effect of the cooling air flowing through passageways 24 and 25 onto the stator and rotor vanes, as described, either or both of the opposed surface portions of the rotor and stator elements, which are situated immediately below the vanes, are provided with heat-dissipating fins, which, in the preferred embodiment, take the form illustrated in Figs. 1 and 2, comprising a series of radially spaced ribs or ns, extending concentric-ally about the rotor axis, as illustrated at 29 to 32 inc. Fins 29, 33

preferably are spaced closely together but not in.

contact in order that jointly they may restrict or meter the outward now of cooling air, such restriction or metering being to a preselected eX- tent depending, of course, upon the distance between such fins 25, 55. Additional heat-dissipating fins may also be provided in the annular passageways 25, 25, formed between the stator rings and the rotor shaft. These fins may be mounted or formed on the stator rings or on the rotor shaft or on both. In the embodiment illustrated in Fig. l, they are mounted or formed on the inner peripheries of the stator rings in the form of axially spaced, peripheral ribs, as shown at S3, 3d.

As above stated, the turbine casing I5, preferably takes the form of the inner and outer spaced-apart jackets l5 and I1, into the space 35 between which, cooling air is injected from the compressor, the inner or the outer jacket being provided with suitable exit passageways like 35, Fig. 3, for expelling the cooling compressed air. Either or both of the jackets I6, I1, may be provided with hcat-dissipating iins, the preferred arrangement being that illustrated in Figs. 1 and 3, wherein the inner surface of the inner jacket l5 is provided with a series of axially spaced, upstanding ribs, as at 31, -along which the cooling air is caused to flow. Such ribs may wind about the inner casing i5 in the manner of screw threads whereby air flowing therealong, as mentioned above, is caused to move about such inner casing in a similar manner.

Referring to Fig. 3, additional heat-dissipating means may be provided on the vanes i4 of the rotor element, by connecting the same with an outer peripheral ring 3i), the exterior surface of which has formed thereon a series of axially spaced peripheral iins or ribs as at Ml. In this construction the cooling air exit passages from the turbine housing are so positioned and directed, as shown in Fig. 3, as to direct the cooling air expelled from passages 35 onto the heat-dissipating fins i] of the rotor vanes.

Fig. 4 illustrates, generally at 4i, a rotor disc mounting two sets of axially spaced airfoil vanes or buckets ft2, 53. The opposite surface portions of the rotor disc, which are disposed below the vanes 52, are provided with radially spaced, concentric circular grooves or ribs, as at fbi, 65, for heat-dissipating purposes as aforesaid. In the rotor construction of Fig. 1l, the rotor disc il is of course transversely apertured or slotted in the manner shown at 21 in Fig. 1, causing the cooling air to ow over the opposite surfaces of the rotor disc, including the heat-dissipating fins fill, 45, in the m-anner generally described and explained in connection with Fig. 1.

Fig. 5 illustrates a gas turbine construction in accordance with the invention, which constitutes a modification of that illustrated in Fig. 1, in that no stator rings are interposed between a pair of adjacent rotor elements. Thus, referring to Fig. 5, a pair of rotor discs 50 and 5l, rotating in opposite direction, and provided with peripherally disposed airfoil vanes or buckets 52, 53 respectively, are mounted adjacent one another in axially spaced relation, between journal members 54, 55, thereby to provide between the rotor discs 50, 5I, a radially extending air cooling passage 55. The rotor assembly thus formed is journaled to a turbine housing 51, through antifriction roller or ball bearings, as indicated at 55. The housing 51 encloses the rotor assembly, as shown, and is provided with an annular inlet nozzle 59 extending from the combustion charnbers, this inlet nozzle being provided with angularly spaced guide vanes as at 60, for appropiately directing the hot gases from the combustion chambers onto the impeller blades 52, 53 of the rotor assembly.

For purposes of air cooling the rotor and stator elements, the turbine housing 51 is provided, near its base, with one or more transversely extending passageways or slots, as at 5 I, for the injection of cooling air from the compressor into an inner chamber 52 of the turbine housing. Chamber 52 is partitioned off from the rotor assembly by means of a wall portion 63, the base of which is radially spaced from the rotor assembly to provide an annular passageway therebetween, as shown at 54. The wall portion E3 of the turbine housing is axially spaced from the adjacent rotor disc 5B to provide therebetween a radially extending cooling air passageway 65, which connects with the annular passageway G5. The rotor disc 55 is transversely apertured or slotted as at 66, for interconnecting the radial passages 55 and 55, disposed on opposite sides, respectively, of the rotor disc 50. The rotor disc 5| is similarly apertured or slotted, as at 51, for inter-connecting the radial passageway 56 with the radial passageway 56a, formed between the rotor disc 5i and the opposite side of the turbine housing 51. Beneath the vanes til, 52 and 53, the opposed rotor disc and stator surfaces are provided with radially spaced, concentric, heat-dissipating ns or grooves, as at 53, 5S, of a character and for purposes as described and illustrated in connection with Figures l and 2.

In the construction of Fig. 5, cooling air forced from the compressor through the inlet passage 6 l, will ilow into the chamber 52, thence through the annular passage Sli, and thence radially outward through the successive passages S5, 5B and 55a., between the opposed rotor and stator surfaces provided with the heat-dissipating fins 63, 59, the rotor apertures or slots 5B, B1 serving to distribute the cooling air between the successive radial passages aforesaid.

Fig. 6 illustrates a multi-stage gas turbine, embodying a turbine construction generally similar to that of Fig. l, in association with the combustion system and a compressor unit. The rotor assembly of the turbine comprises the turbine wheels 10, 1Iy 12,rnounted on a rotor shaft 13, these turbine wheels being provided with peripherally disposed airfoil vanes or buckets, as

at 14. The rotor assembly is enclosed within av turbine housing, shown generallyy at 15, within the turbine wheels, stator rings as at 15, these rings being provided with guidevanes as at 18, for appropriately directing the hot combustion gases against and respectively away from the turbine wheel vanes interposed therebetween. The constructions and relative dispositions of the turbine wheels and stator rings, are similar to those of Fig. l, and the air-cooling arrangement of the Fig, 6 construction is generally similar to that of Fig. 1. That is to say, in the Fig. 6 construction, radially extending cooling air passages are provided between opposed rotor and stator surfaces, as at 18a, the rotor discs are transversely slotted, as at-TB, and the inner peripheries of the stator rings are radially spaced from the turbine wheel hubs, as at 80, for interconnecting adjacent radial passages such as 18. Likewise, heat-dissipating ribs o1 ns are provided beneath the vanes on opposed surface portions of rotor and stator elements, as at 8|, these iins being preferably formed in accordance with the Figs. 1 and 2 embodiment above described. The turbine casing l5 is of the hollow construction shown in Fig, l, and consists of inner and outer, spaced-apart jackets 82, 89, the outer surface of the inner jacket being provided with cooling fins 84 similar to those of the Fig. 1 construction.

Air-cooling of thek turbine is effected by the introduction of cooling air from the compressor through a passage 85 in the base of the turbine casing, from whence the air flows into a chamber 86 of the turbine casing, at which point it divides, a portion flowing radially outward through passages such as 81, interconnectingchamber S5 with the air space 88, within the interior of the turbine casing, from whence this portion of the cooling air nowswithin the turbine casing transversely and circumferentiallyacross the heatdissipating fins 8.4 therein, disposed in helicoidal shape to outlet passages such as 89, provided at the opposite end of the turbine casing. The remainder of the cooling air injected into chamber 86 is forced into the interconnected passageways such as 18a, '19, and 80, between the various rotor and stator elements, and flows thence, in part, ra-

dially outward past the heat-dissipating iins 8|, l

within each passage, such as 16a, provided between opposed rotor and stator surfaces. In this way a highly eflicient and effective air-cooling of the entire turbine, including rotor and stator elements as well as the turbine housing, is effected.

The turbine is driven by hot combustion gases supplied from the combustion system illustrated generally at 90, and comprising an annular housing 9|, 92, within which are mounted a series of angularly spaced combustion chambers, or an annular combustion chamber, as at 92a, supplied with fuel from fuel nozzles or burners, as at 93. Mounted on the opposite end of shaft 13 from that of the turbine rotor, is a rotor 94 of a centrifugal air compressor, the stator 95 of which is provided with air passages, as at 96, opening into the combustion housing 9|, 92, from whence the air flows into the combustion chambers 92a at least partially through the perforations, therein, as at 91. The resulting combustion products or hot gases pass thence into the turbine through the inlet nozzle 98.

The lower portion 92 of the combustion chamber housing is transversely perforated or slotted,

as at 9 9', to provide passageways throughl whichv 8. cooling air under pressure is fed from the compressor into an annular air chamber |00, disposed between the combustion housing 92 and the rotor shaft 13. In addition, the portion |0| of the compressor stator 95 is radially spaced from shaft 13 to provide therebetween an annular passageway |02, through which additional cooling air from the compressor is forced into the air chamber |00, from whence the cooling air is.

forced into the turbine, in the manner above described, through the opening 85, interconnecting the air chambers |00 and 86.

The cooling air fed from the compressor may be further cooled before passing into the turbine chamber 86, by circulating the same through a water-cooled, or other liquid-cooled, cooling means such as that illustrated at |03, mounted in the air chamber |00. This cooling means may comprise a flat, tubular member, wound spirally about a form |05, to provide between successive convolutions thereof, air spaces such as |06, through which the air from the compressor is fed in the direction indicated by the arrows. Cooled water or other cooled liquid is circulated through the tubular member |04 in a circulatory system including pump and an aircooled radiator, through which the liquid is continuously pumped.

Reverting to the combustion chambers 92a, these are preferably provided on the exterior surfaces thereof, with spaced, heat-dissipating ns, as at |01, which preferably take the form of spaced, longitudinally-extending ribs, as shown.

What is claimed is:

1. ln a gas turbine, a disc-like rotor having peripherally disposed bucket means, a housing enclosing said rotor and comprising an inner jacket and an outer jacket, said inner jacket mounting a pair of stator rings disposed on opposite sides respectively of said rotor, said stator rings having guide vanes positioned to direct a hot gaseous stream against and away from said bucket means respectively, said stator rings being spaced axially, and at least one of said rings being also space-d radially, from said rotor to provide passages for the flow of cooling air therebetween, said rotor being perforated to connect said passages, said inner jacket being spaced from said outer jacket for the flow of cooling air therebetween, and said inner jacket being slotted adjacent said rotor bucket means for directing said cooling air thereagainst.

2. In a gas turbine, a disc-like rotor having peripherally disposed bucket means, a housing enclosing said rotor and comprising an inner jacket and an outer jacket, said inner jacket mounting a pair of stator rings disposed on opposite sides respectively of said rotor, said stator rings having guide vanes positioned to direct a hot gaseous stream against and away from said bucket means respectively, said stator rings being spaced axially, and at least one of said rings being also spaced radially, from said rotor to provide passages for the flow of cooling air therebetween, said rotor being perforated to connect said passages, said inner jacket being spaced from said outer jacket for the flow of cooling air therebetween, and said inner jacket being slotted adjacent said rotor bucket means for directing said cooling air thereagainst, said rotor disc and stator rings being provided with heat dissipating fins on opposed surface portions thereof, disposed beneath said bucket means and vanes respectively, and at least one of said jackets being provided with heat dissipating iins.

3. In a gas turbine, a disc-like rotor having peripherally disposed bucket means, a housing enclosing said rotor and comprising an inner and an outer jacket, said inner jacket mounting a pair of stator rings disposed on opposite sides respectively of said rotor, said stator rings being provided With vanes for directing a hot gaseous stream against and away from said rotor bucket means respectively, said stator rings being spaced radially, and at least one of said rings being also spaced axially, from said rotor to provide passages for the injection, under pressure, of cooling air therebetween, said rotor being perforated for connecting said passages, said inner jacket being spaced from said outer jacket, for the injection, under pressure, of cooling air therebetween, and said inner jacket being slotted adjacent said bucket means for exit of said cooling air thereagainst, opposed surface portions of said rotor disc and stator rings, disposed beneath said bucket means and Vanes respectively, being provided with radially spaced heat dissipating ns, concentric with said rotor axis, said bucket means being provided about the outer periphery thereof with axially spaced, outwardly 10 projecting heat dissipating fins, and at least one of said jackets being provided with spaced, heat dissipating ns.

SECONDO CAMPINI.

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